An aerostat is an inexpensive and efficient way to raise a payload in the sky. They are quite insensitive to weather and work equally well in both tropical and arctic climates. Typical payloads are day and night cameras, surveillance radars, VHF and UHF repeaters, TV and radio transmissions. Filled with helium and fitted with an air ballonet to compensate for changes in temperature and altitude, tethered aerostats can be made in almost any size. Smaller aerostats can be easily packed away and reinflated in only half an hour. The complete system of the tethered aerostat supplied by Lindstrand Technologies consists of the aerostat, the mooring station, the winch and tether cable. The latter is normally made from Kevlar and carries both the power supply to the aerostat and fibre optics for communications. The cable has a copper outer sheath to protect the aerostat from lightning strikes.
Surveillance carried out from a tethered aerostat has many advantages over other means of surveillance. Maintenance and operational costs are relatively low, especially when compared to the expense of an aeroplane, where running costs after initial outlay is high, and only a small crew is needed to launch and in-haul the aerostat. The technical aspects of the aerostat’s engineering and construction mean that it is incredibly durable with a large aerostat able to withstand a high level of turbulence if flying away from the surface effect. Being a stable platform also ensures optimum performance from the sensing payload. One of the main advantages over ground-based systems is the wider range of coverage attained from being airborne. Also, the aerostat is able to detect targets that may be obscured from a ground-level perspective. Additionally, as a payload-carrier, the aerostat can easily be adapted to add to, or change the surveillance method.
GA-019 Tethered Aerostat
The GA-019 tethered aerostat itself is a “blimp” envelope (no internal framework). The aerostat’s control system is powered by a compound tether. The mooring station is trailer-mounted, to provide the end-user with the facility to operate at various sites and elevations. Carriage of a payload is the aerostat’s main purpose. For this aerostat system, the payload is carried within a modular aluminium frame structure, to enable the customer to modify the frame with ease, or mount various pieces of their own equipment in their own configuration. A pair of “keder” rails are mounted to the belly of the aerostat envelope, these allow the payload frame to be moved fore and aft if any trimming of the aerostat is necessary due to varied load configurations and centre of gravity. The structure of the GA-019 is designed for aerodynamic efficiency – to achieve maximum stability in flight and to minimise drag. To aid this, the aerostat employs a number of methods such as automatically inflated inner structures and the latest advances in material technology. The envelope consists of three inflated structures; the main hull, the fins and the ballonet. The main hull is filled with helium to provide lift, and is made from fabric chosen for its ability to withstand the effects of the wind, rain, the sun’s UV rays, and other environmental concerns.
GA-025 Parachute Training Balloon
The GA-025 Parachute Training Balloon (PTB) is an economical, inexpensive and proven system for training in static line jumping with minimum cost for maintenance using small number of personnel. Cost of procurement, operations and maintenance of the PTB is minimal compared to the cost of using transport aircraft. The PTB gives the essential independence required to plan and execute training programmes without the restriction of aircraft availability. Typically, the PTB is inflated inside a storage hangar and secured to a truck mounted winch by a steel cable. The gondola is attached to the balloon and the unit is driven to an adjacent dropping zone for jumping. Upon reaching drop zone, the PTB is operational within minutes. Up to seven parachutists and a dispatcher enter the gondola and connect their static lines to the anchor point. The flying cable is paid out and the balloon rises to a typical jump height of 250 to 300 meters (800 – 1000 ft). Jumps can be executed in wind conditions up to 16 knots. Once certain conditions are satisfied, the trainees are dispatched and make their parachute descent from the gondola. On completion of detail the balloon is winched down and the cycle is repeated. After completion of the training programme, the balloon system is secured inside a hangar until required for the next programme.